Squamous cell carcinoma is the most common type of malignant transformation in mature cystic teratomas. It mainly effects postmenopausal women but is rarely seen in young patients. Carbohydrate antigen 19-9 (CA19-9) tumor marker is a high-molecularweight glycoprotein, frequently elevated in gastrointestinal adenocarcinomas. CA19-9 levels can increase in both dermoid cysts and in malignant transformation of dermoid cysts. Herein we report a case of squamous cell carcinoma originating from a dermoid cyst in a 31-year-old, gravida 0, para 0, single woman with high levels of CA19-9 and normal levels of CEA. Preoperative CA19-9 was 1000 U/ml (normal range below 27 U/ml). The patient underwent unilateral salpingo-oophorectomy, omentectomy, appendectomy, pelvic and paraaortic lymphadenectomy. After the pathologic analysis of the material, the patient was categorized as FIGO Stage IIa due to metastasis to the left tube. She received six cycles of cisplatin and paclitaxel at 21-day intervals. The postoperative first day, second month, and sixth month CA19-9 values were 602 U/ml, 33.5 U/ml and 22.3 U/ml, respectively. She is now doing well without recurrence of disease six months after the surgery. Squamous cell carcinomas originating from dermoid cysts are rare tumors especially seen in elderly patients with high levels of tumor markers (like CEA, SCCA). Every case may not have the same characteristics and management should be individualized.